Expansion projectile

ABSTRACT

An expansion projectile (1) with a projectile body (2) forms a central arbor (3) at its end face and a collar (4) coaxially surrounding the arbor (3), where the collar (4) has an outer shape (6) tapering towards the free collar edge (5), and between collar (4) and arbor (3) there is provided a cavity (7) open towards the front. In order to achieve a monobloc projectile free from lead with a high efficiency and a wide range of applications in an economic way, the arbor (3) consists of shaft (31) and tip (32) the collar (4) touches the arbor (3) at least in the transition area (33) between shaft (31) and tip (32), and the arbor (3) protrudes at least up to the axial height of the collar edge (5).

This invention relates to an expansion projectile with an integralprojectile body which at its end face forms a central arbor and a collarcoaxially surrounding the arbor, where the collar has an outer shapetapering towards the free edge of the collar, and between collar andarbor a cavity is provided which is open towards the front.

Expansion projectiles, which upon impact on a soft target mediummushroom open through cavities open towards the front in the vicinity ofthe nose of the projectile and due to the related expansion lead to agreat shock effect, are available in all kinds of variants, and inaccordance with U.S. Pat. No. 3,881,421 it is also already known to forminside this cavity a forwardly directed, bluntly rounded arbor, so thatduring the penetration into the target medium after the first expansionof the collar surrounding the arbor, the medium is opened by theprotruding arbor and expansion is facilitated. These projectiles mostlyconsist of a core of soft, but heavy metal, in particular lead, in orderto achieve a sufficient projectile weight despite the cavity, and of aprojectile jacket of hard metal, preferably copper, copper alloys orsoft iron, in order to improve the firing conditions through the barrelof a weapon. Expansion projectiles in a monobloc design made of copper,copper alloys or soft iron or the like have not gained acceptance sofar, as they must mostly be machined and have a reduced weight ascompared to a lead-core projectile. However, the expansion projectilesmade of lead or with a lead core produce splinters when mushrooming openin the soft target material, or at least during the penetration into thetarget medium a considerable abrasion of lead occurs at the surface ofthe deformed projectile, which involves a very undesired dangerouscontamination, so that it is desired to largely avoid lead and leadalloys in the production of projectiles. Moreover, due to theirexpansion effect the known expansion projectiles exhibit only a smallpenetration effect when striking on a hard target material, and inpractice can therefore only be utilized for a special ammunition. Lastbut not least, the cavities at the nose of the projectile frequentlylead to difficulties when feeding a bullet from the magazine into thebarrel of a self-loading weapon, which in part already requires theclosure of the cavity by means of a special cap, which cap, however,substantially complicates the production of projectiles, as is shown inU.S. Pat. No. 4,136,616, and does still not involve any protectionagainst jams.

It is therefore the object underlying the invention to eliminate thesedeficiencies and create an expansion projectile as described above,which can be produced economically as a monobloc projectile withoutusing lead or lead alloys, which is characterized by its wide range ofapplications and penetrates into soft target medium without producingsplinters, and which, last but not least, is fully suitable forautomatic weapons.

This object is solved by the invention in that the arbor consists ofshaft and tip, that the collar touches the arbor at least in thetransition area between shaft and tip, and that the arbor protrudes atleast up to the axial height of the edge of the collar. There isobtained an integral projectile body, which can be produced withcomparatively little effort in a multi-stage pressing operation from acylindrical starting material, so that this monobloc projectile can alsobe produced as desired from copper, a copper alloy such as tombac, orsoft iron. Since collar and arbor only leave a relatively small cavity,a rather high weight is achieved as compared to other expansionprojectiles, so that lead cores and the like can be omitted without aloss in firing efficiency. For this purpose, collar and arbor are mostlypressed against each other along the entire height of the arbor shaft,but in exceptional cases there may also be left a narrow ring-shapedcavity between collar and arbor in the vicinity of the shaft, whichinvolves the advantage that the press-in resistance of the projectileinto the grooves of a fire arm barrel is smaller than in the firmlypressed embodiments, and thus the maximum gas pressure is also slightlysmaller. The arbor protruding with its tip towards the edge of thecollar or beyond forms such a small cavity together with the surroundingedge of the collar that it is sufficient to unroll and mushroom open thecollar upon impact on a soft target medium, which expansion iscorrespondingly improved by the leading arbor, but that it no longercauses such mushrooming open when the projectile strikes on a hardtarget medium, and upon impact the edge of the collar is urged againstthe tip of the arbor and the projectile reacts like a full-jacketprojectile. On the one hand, splinter-free expansions with a high shockeffect are therefore achieved in a soft target medium, and on the otherhand great penetration effects are achieved in a hard target medium.Care should, however, be taken that the free height of the collar fromthe transition area between shaft and tip of the arbor on the inside upto the edge of the collar corresponds to not more than the length of asurface line of the arbor tip extending in an axial plane from thistransition area to the axis, so that when pressing the edge of thecollar against the tip of the arbor at the end face, the edge of thecollar cannot be compressed beyond the tip of the arbor, which wouldinvolve the risk of unrolling. The arbor correspondingly protrudingupwards also leads to a high dimensional stability of the projectile,which involves favorable ballistic properties and above all avoidsdifficulties when feeding the projectile to the barrel of self-loadingweapons.

When the shaft substantially has an axially symmetrical shape withstraight axially parallel generatrixes or with generatrixes inclinedforward towards the axis, and when the adjoining tip has anobtuse-angled axial section, there are obtained favorable conditions forthe production of the projectile body by means of a pressing method, andit is possible to perfectly place the collar against shaft and tip ofthe arbor, which is important above all in the tip area of the arborupon impact on a hard target medium. The shaft of the arbor will mostlyhave the shape of a cylinder or a truncated cone, but it is alsopossible to design the shaft in the shape of a prism or a truncatedpyramid, which when placing the collar against tip and shaft producesnotch-related preset breaking points along the edges, which facilitate amushrooming open of the collar due to its division into strips.

When the collar is pressed in radially in the edge portion, theprojectile diameter will decrease more towards the tip than by the mereouter shape of the collar, which improves the suitability of theprojectile for self-loading weapons.

The collar may also be pressed against the arbor tip in the edgeportion, so that the size of the cavity open towards the front isminimized and the suitability of the projectile as a full-jacketprojectile can be increased.

In order to improve the mushrooming open of the projectile body uponimpact on a soft target medium independent of the design of the arbor,the collar may have preset breaking points in the edge portion, whichdue to the stripwise division of the collar facilitate unrolling thecollar against the firing direction. It is possible to provide thepreset breaking points by means of notches or the like at the inside oroutside of the jacket or only at the collar edge.

To achieve a special penetration effect even in the case of very hardobjects such as steel, bullet-proof glass or the like, a sheath of hardmaterial may be put over the arbor, which can also influence theprojectile weight.

In accordance with a further aspect of the invention, the projectilebody has a recess on its bottom, which possibly extends into the arbor.This recess may remain hollow in order to reduce the projectile weight,but to increase the weight it may also be filled with specifically heavymaterial such as tungsten, bismuth etc., and it also offers thepossibility to fill in a chemical mass producing a luminous trace uponfiring.

When the arbor has a cavity open towards the tip, the expansion effectmay be increased for special cases, as upon impact on soft target mediumboth the collar and the arbor will unroll.

In the drawing, the subject-matter of the invention is illustratedschematically, wherein:

FIGS. 1 and 2 represent an inventive expansion projectile in a partlysectional side view and in a cross-section along line II--II of FIG. 1,

FIGS. 3 and 4 represent this expansion projectile upon striking on asoft or hard target medium in an axial section,

FIG. 5 represents a modified embodiment of an inventive expansionprojectile in an axial section,

FIG. 6 represents a further embodiment of an expansion projectile in across-section,

FIGS. 7 to 12 represent various embodiments of an inventive expansionprojectile, each in an axial section, and

FIGS. 13 to 15 illustrate the production of an inventive expansionprojectile with reference to three production steps, each in afunctional diagram.

In accordance with FIGS. 1 and 2 an expansion projectile 1 consists of aprojectile body 2, which at its end face verges into a central arbor 3and a collar 4 coaxially surrounding the arbor, where the collar 4 hasan outer shape 6 tapering towards the collar edge 5, and between collar4 and arbor 3 there is provided a cavity 7 open towards the front. Theprojectile body 2 is made as monobloc, preferably of copper or a copperalloy or of soft iron, and to increase the weight related to the totalvolume, arbor 3 and collar 4 are largely closely pressed against eachother. The arbor 3 forms a shaft 31 and a tip 32, it protrudes up to theaxial height of the collar edge 5, and the collar 4 touches the shaft 3at least in the transition area 33 between shaft 31 and tip 32.

There is obtained a monobloc projectile free from lead, which due to theonly small cavity 7 in the tip portion nevertheless has a comparativelyhigh projectile weight. Due to the particular design of arbor and jacketthis expansion projectile reacts like a usual expansion projectile whenpenetrating into a soft target medium with the collar 4 mushrooming open(FIG. 3), which leads to a high shock effect, but upon impact on a hardtarget medium it behaves like a full-jacket projectile with a highpenetration effect, as due to the impact on hard surfaces the edgeportion of the collar 4 is pressed against the arbor tip 32 (FIG. 4). Bymeans of specific design differences between arbor and collar, theexpansion effects or full-jacket effects can be influenced as desired,where preset breaking points 8 in the edge portion of the collar 4 leadto the collar 4 unrolling in segments against the firing direction andmay thus additionally improve the expansion.

Due to the upwardly protruding arbor 3 and the contact between arbor 3and collar 4 in the transition area 33 from the shaft 31 to the tip 32,the collar 4 of the projectile 1 is supported on the inside withdimensional stability, which provides favorable ballistic properties,and the projectile is in addition suitable for self-loading weapons.

The expansion projectile in accordance with the invention can be adaptedin various ways to special objects and effects, without having to bechanged in its basic structure:

In an expansion projectile 101 in accordance with FIG. 5, the basic body102 is equipped with an arbor 103 and a collar 104, which collar 104touches the arbor 103 merely in the transition area 133 between shaft131 and tip 132, so that between the collar 104 and the arbor shaft 131an annular gap 171 is left, which reduces the press-in resistance of theprojectile 101 into the grooves of the barrel of a weapon. This annulargap 171 does not contribute to the expansion effect as a result of thecavity 107 between arbor tip 132 and collar edge 105, which is opentowards the front. As is indicated in broken lines, the arbor 103 mayalso have a cavity 115 open towards the tip 132, so that collar 104 andarbor 103 mushroom open upon impact on a soft target medium, and theexpansion effect is increased. In addition, this cavity 115 contributesto an increase of the radial elasticity of the basic body 102.

In accordance with FIG. 6, the arbor 203 of an expansion projectile 201may have a polygonal, for instance hexagonal cross-section, so that theedges 234 pressed into the inner wall 241 of the collar 204 producepreset breaking points, which act like the notches 8 in the vicinity ofthe collar edge 5 shown in FIGS. 1 and 2 and facilitate the unrolling ofthe collar 204 upon impact on a soft target medium.

In accordance with FIG. 7, the expansion projectile 301 with its basicbody 302 forms an arbor 303, which has an axially symmetrical shape witha straight generatrix E inclined forward towards the axis A, where acircular cross-section provides a truncated cone, or a polygonalcross-section provides a truncated pyramid. The associated collar 304conforms to the arbor shaft 331. The tip 332 adjoining the shaft 331 hasa blunt conical axial section, i.e. in an axial section the openingangle a is at least 90°.

In accordance with FIG. 8, there is provided an expansion projectile401, where the collar 404 is pressed against the arbor 403 along theentire inner wall, so that the area of the collar edge 405 also rests onthe surface of the arbor tip 432. There is only left a very small cavity407 open towards the front, so that the full-jacket effect of theprojectile is increased.

In accordance with FIG. 9, the expansion projectile 501 is designed toalso penetrate through particularly hard objects, for which purpose asheath 9 of hard material, for instance a steel cap, has been put ontothe arbor 503. Here as well, largely pressing the collar 504 against thesheath 9 of hard material, which has a shape conformal to the arbor 503,provides for rather small cavity 507 open towards the front.

In accordance with FIG. 10 an expansion projectile 601 is illustrated,whose projectile body 602 verges at its end face into an arbor 603 and acollar 604 coaxially abutting against the arbor. The projectile body 602is, however, provided with a recess 10 open at the bottom, which may forinstance accommodate a chemical mass producing a luminous trace uponfiring, but may also remain hollow to influence the projectile weight,or may be filled with a specifically heavy material.

In accordance with FIG. 11 there is shown an expansion projectile 701 tobe used for hunting, where the arbor 703 protrudes over the edge 705 ofthe collar 704 with a narrow tip 732.

In accordance with FIG. 12 there is illustrated a similar expansionprojectile 801 to be used for hunting, whose arbor 803 with its bluntarbor tip 832 again protrudes into the axial height of the collar edge805 of the collar 804. The projectile body 802 is provided with a recess810 at its bottom and is fitted with an additional weight 11 of aspecifically heavy material such as tungsten or bismuth, but also lead.

As is illustrated in FIGS. 13, 14 and 15, an expansion projectile 1 inaccordance with the invention can be produced in few steps by means of apressing method largely without machining, where a cylindrical blank 1ais employed. In accordance with FIG. 13, this blank 1a is placed in apressing tool 12 comprising a female mold 13 and a male mold 14, and ina first pressing step is pressed to a frustoconical blank 1b with arborand collar. In the following pressing step shown in FIG. 14, this blank1b is put into a pressing tool 112 comprising a female mold 113 adaptedto the blank and a suitable male mold 114, so that with this tool a rawprojectile 1c of a cylindrical basic shape with collar and arbor ismade, whereupon in the next pressing step shown in FIG. 15 a suitabletool 212, which has a corresponding female mold 213 and a suitable malemold 214, is used for pressing the finished expansion projectile 1 fromthe raw projectile 1c, where the notches at the edge provided for thepreset breaking points in the collar can be impressed already at thismethod step. Depending on the special shape of the projectile or theassociated arbor or collar, this pressing method can of course becompleted and expanded to the required extent by additional methodsteps.

What is claimed is:
 1. An expansion projectile comprising a monoblocprojectile body having an end face, the end face of the monoblocprojectile body formed by(a) a central arbor consisting of(1) a shafthaving an axis and (2) a tip, and (b) a collar having a free edgeradially pressed inwardly toward the axis,(1) the collar coaxiallysurrounding the central arbor and having an outer shape tapering towardsthe free edge, (2) a cavity being defined between the central arborshaft and the collar, the cavity being open towards the end face, (3)the collar touching the central arbor shaft at least in a transitionarea between the central arbor shaft and tip, and (4) the central arborshaft protruding at least to the axial height of the free collar edge.2. The expansion projectile of claim 1, wherein the central arbor shaftis substantially axially symmetrical, and the central arbor tip has anobtuse-angled axial section.
 3. The expansion projectile of claim 2,wherein the central arbor shaft has straight generatices extendingparallel to the axis.
 4. The expansion projectile of claim 2, whereinthe central arbor shaft has generatrices inclined towards the axis inthe direction of the end face.
 5. The expansion projectile of claim 1,wherein the free collar edge has been pressed inwardly against thecentral arbor tip.
 6. The expansion projectile of claim 1, wherein thefree collar edge has preset breaking points.
 7. The expansion projectileof claim 1, wherein the monoblock projectile body has a recess at an endthereof opposite to the end face.
 8. The expansion projectile of claim7, wherein the recess extends into the central arbor shaft.
 9. Theexpansion projectile of claim 1, wherein the central arbor shaft has acavity open towards the tip.